Robust and Error-Tolerant Peg-In-Hole Assembly Using Simple Control
Masanori Ueda, Tokuo Tsuji, Shota Ishikawa, Tatsuhiro Hiramitsu, Hiroaki Seki, Yosuke Suzuki, Toshihiro Nishimura, Tetsuyou Watanabe
AI summary
Problem
Automated peg-in-hole assembly traditionally demands high-precision alignment, expensive high-frequency sensors, and complex active control systems, which are costly and sensitive to environmental variations.
Approach
The method leverages a flexible-jointed gripper to passively rotate the peg around a contact point, using force-torque data to estimate contact position and tilt the peg in the opposite direction for successful insertion.
Key results
- Mechanical analysis of peg rotation dynamics under flexible joint compliance
- Contact position estimation via averaged orthogonal moment vectors from bidirectional rotation
- Successful insertion with random position errors up to 8 mm and orientation errors up to 5° tilt
- Demonstration of robust assembly without high-frequency sensors or complex active controllers
Why it matters
Provides a cost-effective, reliable alternative for industrial automation by simplifying hardware and control requirements while maintaining high error tolerance.
Abstract
We developed a simple peg-in-hole strategy that uses flexible joints and peg rotations. Even when the circle peg in the peg-in-hole assembly contains position and orientation errors, it can be inserted in a passive and robust manner. Additionally, using force-torque sensors to estimate the contact position allows the correction of the orientation of the peg and its insertion into the hole if the initial attempt fails. We conducted horizontal and vertical peg-in-hole experiments with random position and orientation errors to demonstrate the effectiveness of the developed method. This method does not rely on high-frequency sensors or servos, which enables a quick and low-cost peg-in-hole assembly with tolerance to position and orientation errors and direction.